Appeal to ignorance

This is when a position is claimed to be true simply because it has not been proven false.

For example: “There must be life in out space. No one has ever proven that there isn’t“. Just because no one has been able to disprove a claim does not mean the claim is true. An appeal to ignorance can always be rebutted by an appeal to ignorance. You can respond by saying “There cannot be life in outer space since no one has ever proved that there is“. The lack of evidence AGAINST a position is not the same as evidence FOR a position.